Handle malformed and IPv6 config addresses

config/user_config.go

@@ -6,6 +6,7 @@ import (
 	"git.stormux.org/storm/barnard/uiterm"
 	"github.com/pelletier/go-toml/v2"
 	"io/ioutil"
+	"net"
 	"os"
 	"strconv"
 	"strings"
@@ -367,7 +368,7 @@ func readFile(path string) []byte {
 
 func fileExists(path string) bool {
 	info, err := os.Stat(path)
-	if os.IsNotExist(err) {
+	if err != nil {
 		return false
 	}
 	return !info.IsDir()
@@ -389,11 +390,16 @@ func resolvePath(path string) string {
 }
 
 func makeHostPort(addr string) (string, int) {
-	parts := strings.Split(addr, ":")
+	// SplitHostPort correctly handles bracketed IPv6. Invalid or portless
-	host := parts[0]
+	// addresses stay usable as a host with Mumble's default port instead of
-	port, err := strconv.Atoi(parts[1])
+	// crashing configuration operations.
+	host, portText, err := net.SplitHostPort(addr)
 	if err != nil {
-		panic(err)
+		return strings.Trim(addr, "[]"), 64738
+	}
+	port, err := strconv.Atoi(portText)
+	if err != nil || port < 1 || port > 65535 {
+		return host, 64738
 	}
 	return host, port
 }

config/user_config_test.go

@@ -37,6 +37,19 @@ func TestConfigBackfillsRecordingDefaults(t *testing.T) {
 	}
 }
 
+// Regression: malformed and IPv6 addresses were split at every colon and
+// could panic while merely reading a saved user preference.
+func TestMakeHostPortHandlesIPv6AndMalformedAddress(t *testing.T) {
+	host, port := makeHostPort("[2001:db8::1]:64739")
+	if host != "2001:db8::1" || port != 64739 {
+		t.Fatalf("got %q:%d", host, port)
+	}
+	host, port = makeHostPort("not-a-host-port")
+	if host != "not-a-host-port" || port != 64738 {
+		t.Fatalf("got %q:%d", host, port)
+	}
+}
+
 func TestConfigUsesHomeEnvironmentForDefaultPath(t *testing.T) {
 	dir := t.TempDir()
 	t.Setenv("HOME", dir)